Means for skimming off froth



Get 13, 1925. 1,557,369

J. W KLEINBENTINK MEANS FOR SKIMMING OFF FROTH Filed Nov. 6, 1923suitable Patented Get 13, 1925..

- STA JAN WILLEM KLEINBENTINK, 0F HOE-NSBROEK, LIMBURG, NETHERLANDS,ASSIGNOR T0 NAAMLOOZE VENNOOTSCHAP VEREENIGDE KOLE'NMAATSGHAPPI-l' EN'IER VOO'RTZETTING DEB STEENKOLENZAKEN, GEDREVEN' DOOR DE N. V. FURNESSKOLENMAATSGHAPPIJ EN HOVMT EN HENNYS HANDELMAATSCHAPPIJ, 0F ROT-TER'DAM, NETHERLANDS, A COMPANY ORGANIZED UNDER THE LAWS OF THENETHWAND'S.

MEANS FOR SKIMMING OFF FROTH.

Application filed November s, 1923. Serial at. 673,208.

To all whomt't may concern:

Be it known that 1, JAN WILLEM KLEIN- BENTINK, a, subject of the Queenof the Netherlands, residing at Hoensbroek, Limburg, Netherlands, haveinvented ccertain new anduseful Improvements in Means for Skimming OERFroth, of which the following is a specification.

This invention relates to improved means for skimming off froth, suchmeans being applicable for instance in apparatus for refining coalslimes in accordance with the froth flotation process. With known meansof this character it is not possible to skim the aqueous blanket 0d thesurface of the liquid from which the froth has developed withoutbreaking up part of the bubbles, especially when the bubble formation isvery fragile and has bad lasting qualities.

The present invention comprises means for skimming off frothoverlyingthe surface of liquid in a vat, consisting of stationary androtary skimming elements, either the stationary or rotary elements beingrigid while the others are yieldable so as to enable themto pass overeach other.

The annexed drawing illustrates a novel froth skimming apparatus made inaccordance with the present invention and which is capable of removingthe aqueous blanket of froth without deteriorating it.

Figure 1 is a plan view of a circular froth containing vat provided withskimming apparatus in accordance with the invention, Figure 2 being avertical sectional View thereof.

Figure 3 shows the elevational view of a detail, viz. a stationaryyielding wall adapted for co-operation with rotary, rigid skimmingblades, whereas Figures shows the cross-sectional view of said yieldingwall.

In these drawings a conical mixing vat a, in which the froth form isproduced in a manner, is ii communication through openings 1) near itsbottom with a surrounding annular froth containing vat 0 in the form ofa downwardly pointing cone, into which the. froth developed in vat a isadapted to be transferred and in which the bubbles rise to the surfaceof the liquid.- Two rigid, spirally curved-skimming blades e are mountedfor slow rotary movement about a vertical spindle all in the directionof the arrow; during this rotation the blades 6, the lower edges ofwhich extend below the surface of the liquid, force the froth outwards.Arranged between the wall of the mixing vat a and that of the frothcontaining vat 0 is a plurality of radial, stationary skimming elementsor walls 7', extending with their upper edges above the froth blanketand with their lower edges some distance below the surface of theliquid. These stationary walls are adapted .to yield in the direction ofrotation of the skimming blades 6, so that the latter can pass overthem. As shown in the drawing, each wall 7 is composed of a plurality ofnarrow, metal strips h arranged side by side and each weighted as at g,said strips being pendulously suspended from a shaft 5 a slight distanceabove their centres of gravit y 1 During rotation of a blade 6 the spacebetween this blade and the wall f next to it in the direction ofrotation gradually decreases. The froth in this space is retained by theupright wall f, so that the blade 6 acts to skim the froth 0d over theupper edge of the froth containing vat. As soon as that part of theblade e which is adjacent tothe mixing vat a engages the inner strip hof wall f said strip yields so as to allow the blade e to pass, afterwhich the wall slowly resumes its upright position. During this slowoscillation of the strip h the liquid is not appreciably agitated sothat the froth blanket is not damaged. The other strips h of wall fconsecutively perform the same movements.

The manner-in which blades e are driven is of subordinate importance asfar asthe (I present invention is concerned. In the exright position; inthis case the strips need not extend into the liquid through anyappreciable distance so that they hardly agitate the liquidwhenoscillating. Furthermore, the yielding walls f could be rotatableabout axis d when the rigid skimming blades e would have to bestationary.

Equally good results would be obtained by makingthe skimming blades. eyielding and the retaining walls f rigid. These and other modificationsfall within the spirit and scope of the invention as expressed in theaccompanying claims when broadly construed.

The novel apparatusmade in accordance with the present invention, hasmoreover, the advantage of being cheap to-manufa'cture and reliable inoperation. 7

Having now particularly described and ascertained the nature of my saidinvention to contain a liquid with surface characteristics induced byfroth flotation, of skimming means to remove the froth, including arotary skimming element and a relatively fixed skimming element, saidelements being adapted for actual and displaceable contact in operation,said rotary element having a convex pressure :face and the fixed elementbeing directly radial of the vat.

3. The combination with a vat adapted to contain a liquid-with surfacecharacteristics induced by froth flotation, of 'skimming means to removethe froth, including a radial element made up of a series of indetupendently movable sections, and a rotating element having a convexpressure face operating in part in a path including the radial element,said rotating element displacingthe sections of the radial element insuccession. w v

4. The combination with a vat adapted to contain a liquid with surfacecharacteristics induced. by froth flotation, -of skimming means toremove the froth, including a radial element gnade up of a series ofindependently movable sections, a rotating element having a convexpressure face operating in part in a path including the radial element,said rotating element displacing the sections of the radial element insuccession, and means for returning said sections of the radial elementto normal position.

5. Thecombination with a vat adapted to contain a liquid with surfacecharacteristics induced by froth flotation, of skimming means to removethe froth, including an ele ment extending radially tothe edge of thevat-and made up of a series of independently movable sections, arotating element having a convex pressure face operating in part in apath including the radial element, said rotating element displacing thesections of the radial element in succession,-and means resisted by thebody of liquid in the vat to slowly return said sections to-normalposition, whereby to avoid undue agitation of the froth area.

6. A conical mixing vat adapted to contain aliquid with surfacecharacteristics induced by froth flotation, aplurality of rela-. tivelyfixed walls extendin radially and" throughout the full radial listanceof the v'at, and a series of movable skimming eleinents, each having aconvex pressure face and operating throughout a linear distance in thevat materially greater than the radial distance, and means for operatingsaid movable elements the relatively fixed walls being displaceablethrough contact with the movable elements.

In testimony whereof I aifix my signa re. 4 v

JAN'IWILLEM KLEINBENTINK.

